Olive oil consumption linked with lower risk of dementia-related death

Consuming olive oil is associated with lowering the risk of dementia-related death compared to rare or no consumption of it - regardless of overall diet quality - according to an NIA-funded study. The findings, published in JAMA Network Open, suggest that an eating pattern that incorporates olive oil may support brain health.

Some previous studies have shown that the Mediterranean diet, a dietary pattern that emphasizes olive oil, may help slow cognitive decline. However, few studies have looked at the relationship between olive oil consumption and dementia-related mortality. A team led by Harvard scientists set out to address this gap.

The researchers examined data from the Nurses' Health Study and the Health Professionals Follow-Up Study, two large prospective studies of American adults. In these studies, lifestyle factors and medical history were assessed biennially through mailed questionnaires. Beginning in 1990 and every four years following, researchers monitored olive oil intake through questions on cooking and consumption.

For the current study, researchers analyzed data from a subset of 92,383 participants observed over 28 years, including 60,582 (65.6%) women and 31,801 (34.4%) men. Participants were categorized by olive oil intake frequency: never or less than once per month (reference group); some olive oil, defined as greater than zero to less than or equal to 4.5 grams per day; greater than 4.5 grams per day to less than or equal to 7 grams per day; and greater than 7 grams per day.

Next, the researchers calculated how much olive oil participants consumed over the span of 18 years. They found that participants who consumed more olive oil had a lower risk of dying from dementia. Substituting olive oil for margarine and mayonnaise was associated with a lower risk of dementia-related mortality regardless of overall diet quality.

After analyses of the data, researchers found that participants with the highest olive oil intake had a lower risk for dementia-related deaths. Participants who consumed more than 7 grams per day of olive oil had a 28% lower risk of dying from dementia compared with participants who never or rarely consumed olive oil. Of 37,649 total deaths that the study documented, 4,571 participants died from dementia. Results were consistent after further adjustment for APOE ε4, a genetic risk factor for Alzheimer's disease.

The study has some limitations: It was conducted among health professionals with at least two years of postsecondary education and participants were mostly White. These factors may limit the generalizability of the findings to the broader population. Future research should include more socioeconomically and racially diverse participants. The study furthermore did not differentiate among types of olive oil. Nonetheless, the findings underscore that diet is an important lifestyle factor that warrants future research as a dementia prevention strategy.

This research was funded in part by NIA grant R21AG070375.

NIA leads NIH's systematic planning, development, and implementation of research milestones to achieve the goal of effectively treating and preventing Alzheimer's and related dementias. This research relates to NIH's AD+ADRD Research Implementation Milestone 8.B, "Increase investment in clinical trials that robustly test a variety of lifestyle and other non-pharmacological interventions."

Reference: Tessier A-J, et al. Consumption of olive oil and diet quality and risk of dementia-related death. JAMA Network Open. 2024. Epub May 1. doi:10.1001/jamanetworkopen.2024.10021.